Investigating the evolution of apoptosis in malaria parasites: the importance of ecology

Apoptosis is a precisely regulated process of cell death which occurs widely in multicellular organisms and is essential for normal development and immune defences. In recent years, interest has grown in the occurrence of apoptosis in unicellular organisms. In particular, as apoptosis has been reported in a wide range of species, including protozoan malaria parasites and trypanosomes, it may provide a novel target for intervention. However, it is important to understand when and why parasites employ an apoptosis strategy before the likely long-and short-term success of such an intervention can be evaluated. The occurrence of apoptosis in unicellular parasites provides a challenge for evolutionary theory to explain as organisms are expected to have evolved to maximise their own proliferation, not death. One possible explanation is that protozoan parasites undergo apoptosis in order to gain a group benefit from controlling their density as this prevents premature vector mortality. However, experimental manipulations to examine the ultimate causes behind apoptosis in parasites are lacking. In this review, we focus on malaria parasites to outline how an evolutionary framework can help make predictions about the ecological circumstances under which apoptosis could evolve. We then highlight the ecological considerations that should be taken into account when designing evolutionary experiments involving markers of cell death, and we call for collaboration between researchers in different fields to identify and develop appropriate markers in reference to parasite ecology and to resolve debates on terminology.Host-parasite interactio

Design and analysis of proximate mechanisms for cooperative transport in real robots

This paper describes a set of experiments in which a homogeneous group of real e-puck robots is required to coordinate their actions in order to transport cuboid objects that are too heavy to be moved by single robots. The agents controllers are dynamic neural networks synthesised through evolutionary computation techniques. To run these experiments, we designed, built, and mounted on the robots a new sensor that returns the agent displacement on the x/y plane. In this object transport scenario, this sensor generates useful feedback on the consequences of the robot actions, helping the robots to perceive whether their pushing forces are aligned with the object movement. The results of our experiments indicated that the best evolved controller can effectively operate on real robots. The group transport strategies turned out to be robust and scalable to effectively operate in a variety of conditions in which we vary physical characteristics of the object and group cardinality. From a biological perspective, the results of this study indicate that the perception of the object movement could explain how natural organisms manage to coordinate their actions to transport heavy items

Solutions and Formulae for Some Systems of Difference Equations

This paper is written to provide some solutions to the following systems of difference equations: where the initial data are arbitrary non zero real numbers

Stability, Adsorption and Diffusion of CH4, CO2 and H2 in Clathrate Hydrates

We present a study of the adsorption and diffusion of CH4, CO2 and H2 molecules in clathrate hydrates using ab initio van der Waals density functional formalism [Dion et al. Phys. Rev. Lett. 92, 246401 (2004)]. We find that the adsorption energy is dominated by van der Waals interactions and that, without them, gas hydrates would not be stable. We calculate the maximum adsorption capacity as well as the maximum hydrocarbon size that can be adsorbed.The relaxation of the host lattice is essential for a good description of the diffusion activation energies, which are estimated to be of the order of 0.2, 0.4, and 1.0 eV for H2, CO2, and CH4, respectively.Comment: 4 pages, 4 figures, 3 table

Effect of diet on the quality and quantity of venom produced by Apis cerana

The bee venom samples from honey bee (Apis cerana) foraged on seven plants dominating seven sites in Malaysia were collected. The protein content of the pollen loads of these test plants were tested according to the method of Kjeldahl (AOAC 1990). The samples were analysed to determine the effects of diet type on the quantity and quality of its constituents – melittin, phospholipase A2 and apamin using HPLC. The highest melittin (677.86μg/ml), phospholipase (477.96 μg/ml) and apamin (136.10 μg/ml) content were recorded in venom collected from honey bee colonies foraged on Durian plant which has protein content (31.7%) of its pollen loads. A positive correlation was recorded between the protein content with melittin (R2= 0.9372), phospholipase A2 (R2= 0.7208) and apamin (R2=0.4128), while a negative correlation was observed between the protein content and the weight of the venom mount produced (R2= -0.7549). A direct relationship was observed between the quality of the venom and the protein content of pollen loads, while the quantity of the venom was not in accordance with the venom quality